1. Field of the Present Invention
The present invention relates generally to liquid crystal devices and specifically to reflection-type devices that have reduced double image reflections and improved performance.
2. Description of the Prior Art
Liquid crystal (LC) has the unusual physical characteristic of sharing aspects of both the liquid and solid phases at the same time. Computer and television display screens that are based on LC technology are now widely available. LC displays (LCDs) are typically flat, draw little power, have good contrast, and can be made to produce color.
Prior art reflection-type LCDs use twisted nematic (TN) liquid crystal material with an optically uniaxial opto-electric medium having a quarter wavelength plate with a twist angle of 45.degree.. The output light is very often elliptically-polarized. For a description of such devices, see, U.S. Pat. No. 4,019,807, and Japanese Laid-Open Patent Publication 56-43681. Some prior art reflection-type LCDs use super twisted nematic (STN) mode, which is a variation on the TN mode mentioned.
In prior art reflection-type LCDs, there has been little allowable margin with respect to the thickness of an LC layer, and display performance has been inconsistent. Also, light output is reduced because it is typically elliptically-polarized. Dark and discolored displays and double images are significant problems in prior art LCDs. A liquid crystal device that solves these problems is, therefore, needed for present and future applications.